Apparatus for controlling highway crossing signals



Feb. 10, 1953 J. E. MCMAHON, JR 2,628,306

APPARATUS FOR CONTROLLING HIGHWAY CROSSING SIGNALS Filed May 29, 1948 )L I N i gm' E; Wma' 45 f7 i w46 WSN E @if 255 D I N @5w WSJ-Qd. i *L* 5126 I Fig? Fig? Z IN VEN TOR.

HIS' ATTRNEY Patented Feb. 10, 1953 APPARATUS FOR CONTROLLING HIGHWAY CROSSING SIGNALS .lames E. McMahon, Jr., Wilknsburg, Pa., as-

signor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application May 29, 1948, Serial No. 29,977

Claims. l

My invention relates to apparatus for controlling highway crossing signals, and particularly to apparatus for interrupting the operation of a highway crossing signal when a train stops on a control track section for the highway crossing signal, and for then again starting operation of the highway crossing signal when the train resumes its movement toward the highway crossing.

In order to avoid unnecessarily delaying the users of a highway at the intersection of a railway track with a highway, it is important that the operation of a highway crossing signal shall be interrupted if a train stops on a control track section for the highway crossing signal. It is very desirable to prev-ent useless operation of a highway crossing signal in Order to maintain the respect of users of a highway for the indications given by the highway crossing signal. If a highway crossing signal is unnecessarily operated when it should not be operated, users of a highway may become accustomed to disregarding the indications given by the highway crossing signal, and may sometimes disregard it when such action is dangerous. It is particularly important that means be provided for interrupting the operation of a highway crossing signal if it is so located that some trains stop regularly on a control section for the highway crossing signal, such as at passenger stations, or at points where trains receive fuel, or water, or where helper locomotives are coupled onto trains.

One feature of my invention, in apparatus embodying time element means for interrupting operation of a highway crossing signal when a train approaching the highway crossing signal in a given direction stops on a given control track section, is the provision of means to prevent energization of the time element means when a train moving in the opposite direction recedes from the highway crossing signal.

Another feature of my invention is the provision of means to insure the loperation of a highway crossing signal in event of failure of given control apparatus for the signal.

The apparatus `oi my invention is an improvement over that which is disclosed in the cepending application, Serial No. 33,980, led June 19, 1948, by Kenneth L. Muse, for Apparatus for Controlling Highway Crossing Signals.

I shall describe three forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

lin the accompanying drawings, Fig. 1 is a diagrammatic View showing one form of apparatus embodying my invention, in which a railway track which intersects a highway is divided to form a crossing section at the highway, an approach control section adjacent one end of the crossing section, and also an approach control stretch adjacent the opposite end of the crossing section; in which one rail of the entering end of the approach control stretch of track is divided to form a preliminary control section and a main control section between the preliminary section and the intersection of the railway track with the highway; in which one rail of an intermediate portion of the main control section is divided to form an intermediate section; in which operation ofa highway crossing signal adjacent the intersection of the railway track with the highway is started when a train on the preliminary section enters the adjacent portion of the main control section; in which operation of `the crossing signal is interrupted if a train approaching the intersection stops on the main control section; and in which operation of the highway crossing signal is resumed when the train again proceeds over the intermediate section; Fig. 2 is a diagrammatic view showing a modification of a portion of the apparatus shown in Fig. 1; and Fig. 3 is a diagrammatic view showing a modiiication of the track circuit apparatus shown in Fig. 1.

Similar reference characters refer to similar parts in each of the drawings.

In each of the drawings, the contacts operated by the various relays or by a time element device are identiiied by numbers, each such number having a distinguishing preiix from which it is separated by a dash when the associated contact is shown apart from the relay by which it is operated. The preiix for each of th-e contact numbers comprises the reference character for the respective relay by which the associated contact is operated. For example, contact WS-ZB, shown in Fig. 2 in the circuits for relay l-ZS, is identiiied by the number 28 separated by a dash from the prefix WS which is the reference character for relay WS by which this contact is operated.

Referring further to Fig. 1 of the drawings, a stretch of railway track is shown intersected by a highway H. A highway crossing signal, which may be of the flashing light type or of any other suitable design, but which, in order to simplify the drawing, is shown as a bell G, is located adiacent the intersection of the railway track with highway H.

Rails l and la of the railway track are divided by insulated joints 2 to form a crossing section 2T at the intersection of the railway track with the highway, an aprroach control section 3T adjacent the right-hand end of section 2T, as shown in the drawing, which I shall assume is the east end, and also an approach control stretch of track adjacent the opposite or west end of section 2T. The approach control stretch west of section 2T is divided by an insulated joint 3 in-one of its rails, adjacent its entering or west end, to form a preliminary control section AIT, and a main control section which comprises two portions BIT and CIT An intermediate portion of the main control section is divided by insulated joints 4 in rail I to form an intermediate section ZT which is shorter than the distance between the trucks of a railway car, so that when a train moves over the intermediate section, this section is periodically shunted instead '0f being continuously shunted by the train. Portions BIT and CIT of the main control section are interconnected by a jumper 5 around section ZT.

Each of the track sections 2T `and 3T is provided with la track circuit which includes a relay 2R1or 3R, respectively, connected across the rails adjacent one end of the section, and a suitable source of current, 'such vas a battery 6, connected across the rails adjacent the opposite end of the section.

Two biased neutral track relays, designated by the reference characters AI-R and Bl'R, are connected in series opposition -across the rails of portion CIT vol the main control section of track west of `section 2T. Each of the relays AIR and B'IR is so constructed that, when current ofA a given polarity is supplied toits winding, it will open its back contacts and close its front contacts, whereas when current of the opposite polarity is supplied to its winding, its back contacts will remain closed and its vfront contacts will re main open. The direction of flow of current, to which each of these relays will respond by closing its vfront contacts, is indicated by an arrow within the symbol for the winding of the relay.

It follows that, with relays AIR and BIR connected in series opposition across the' rails vof -portion CIT as shown in the drawing, when cur- Vrent of a given or normal polarity is supplied to these relays from track section portion CIT, relay AIR will close its front contacts I4 and I5, and the front contacts 55 and BIR-3` of relay BIR will remain open, and when current of the opposite or reverse polarity is supplied to these relays from portion CIT, relay BIR will close its `front contacts 55 and'BIR-Sll and the front con- 'is connected in multiple with a resistor 9 around `insulated joint 3. With relays AIR and BlR thusenergized, the front-contacts It and I 5 of relay AlR are closed, and the front contacts 55 and 'BIR-S'Il of relay BIRare open.

When an eastbound train enters preliminary section AFI T, battery l is 'shuntecL `and battery 8 `is connected through vthe wheels and axles ofthe train with rail I of section AIT for supplying current of reverse polarity to portions BET and C'IT ofthe main control section. Relays AIR and BI'R thus become energized by current of reverse polarity, so that the front contacts I4 and I5 of 'relay AIR 'are opened, and the vfront contacts 55 and BiRfS of relay BER become closed. When the train enters section portion BIT, battery 8, as well as battery l, is shunted, so that both relays AIR and BIR become deenergized, and their front contacts are opened.

Intermediate section ZT is provided with a track circuit which includes a suitable source of current, such as a battery in?, connected across the rails adjacent one end of the section, and a relay ZR connected through a resistor II across the rails adjacent the opposite end of the section. Relay ZR may preferably be of higher resistance than the windings of relays AER and BlR.

A repeater relay EP is controlled by front contacts ill and 55 of relays AIR and BIR respectively, connected in multiple so that, when either relay AIR or BIR is energized by current, in response to which its front contacts are closed, relay IP will be energized.

An eastbound control stick relay, designated by the reference character ET, has a pickup and a stick circuit, both of which are controlled by a front contact l5 of relay AlR, and the pickup circuit is also controlled by a front Contact I6 of relay 2R. A westbound control stick relay, designated by the reference character WT, is similarly controlled by relays 3R and 2R.

-An eastbound direction stick relay, designated by the reference character ES, has a pickup and a stick circuit, each of which is controlled by back contacts t3 and lll of relays ET and 2R, respectively, and the pickup circuit is also controlled' by afront Contact 45 of .relay WT and a back contact WS-if3 of relay WS. Relay ES has also a second stick circuit, which is controlled by a back Acontact d5 or relay WT. A westbound direction stick relay WS is controlled similarly to relay ES.

.A checking stick relay ITS has a pickup and a stick circuit each of which is controlled by back contacts 28 and AIR-29 of relays WS and AIR, respectively, and the pickup circuit is also controlled by a front contact EIR-30 of relay BIR, so that, unless relay AIR becomes deenergized and relay BIR becomes energized when a train enters section AIT, relay ITS will not become energized. A second checking stick relay,

`designated by the reference character IeZS, has

a pickup and a stick circuit, each of which is controlled by a front contact 32 of relay ITS, and the pickup circuit is also controlled by a front contact ZR-33 of relay ZR, and the stick circuit is also controlled by a back contact ZR-33 of relay ZR. It follows that, if relay ZR is deenergized for some reason such, for example, as on account of being disconnected from section ZT, relay I-ZS will not pick up when relay ITS becomes energized.

A timing stick relay, designated by the reference character YS, is controlled by relays I-ZS, ZR, and IP, and by time element device TE. When relay I-ZS becomes energized, relay YS will become energized only if relay IP is deenergized on account of both relays AIR and BIR being deenergized. If relay ZR becomes deenergized after relay YS is energized, relay YS will become deenergized because of the reversal of polarity through its winding, eiected by the contacts ZR-4I and ZR-3T of relay ZR.

A time element device, designated by the reference character TE, is controlled by a front contact 42 of relay YS.

A highway crossing signal control relay XR is controlled to become deenergized when a westbound train enters section 3T, or when an eastbound train enters portion BIT of the main control section. If a suflicient period of time then elapses for time element device TE to close its front contact 21 before the eastbound train enters section ZT, relay XR will again become energized and interrupt the operation of crossing signal G.

Referring next to Fig. 2, in the modication here shown, a single checking stick relay I-ZS is provided instead of the two checking stick relays ITS and I-ZS shown in Fig. 1. All other parts of this form of apparatus are as shown in Fig. 1.

Referring now to Fig. 3, in the modification here shown, a separate track circuit is provided for preliminary section AIT, including a battery I2 connected in series with a track relay AIPR across the rails adjacent one end of section AIT, and a track relay AITR connected across the rails adjacent the opposite end of section AIT. The parts of this track circuit are so proportioned that, With section AIT unoccupied, the front contacts 45 and 52 of relay AIPR Will be open and its back contacts 49 and 52 will be closed, whereas the front contacts 50 and 5I of relay AITR will be closed and its back contacts 50 and 5I will be open.

When a train enters section AIT, relay AITR becomes shunted, so that its front contacts 50 and 5I become open and its back contacts 50 and 5I become closed. With a train on section AIT, sufficient current will be supplied through the winding of relay AIPR and the wheels and axles of the train for causing relay AIPR to close its front contacts 49 and 52 and open its back contacts 49 and 52. Current of normal or reverse polarity is supplied to portion BIT of the main control section, from battery I3, according as the contacts 49 and 52 of relay AIPR are closed at their back points while the contacts 50 and 5I of relay AITR are closed at their front points, or the contacts 49 and 52 of relay AIPR are closed at their front points while the contacts 50 and 5I of relay AITR are closed at their back points.

All other parts of this form of apparatus are as shown in either Fig. l, or in Fig. 1 modified as shown in Fig. 2.

Having described, in general, the arrangement and control of the apparatus shown by the accompanying drawings, I shall now describe, in detail, its operation.

As shown in the drawings, all parts of the apparatus are in their normal condition, that is, each of the track sections is unoccupied, and therefore track relays 2R, 3R and ZR are energized, and relays AIR and BIR are energized by current of normal polarity, so that the front contacts I4 and I5 of relay AIR are closed, and the front contacts 55 and BIR-30 of relay BI R are open; relays IP, ET, WT, and XR are energized; relays ES, WS, ITS, l-ZS, and YS, time element device TE, and crossing signal G are deenergized; and relay AI TR in Fig. 3 is energized, but relay AIPR is energized by insuicient current to close its front contacts.

The circuit by which relays AIR and BIR in Fig. l are energized by current of the given or normal polarity passes from battery 1, through rail I of section AIT and portion BIT of the main control section, jumper 5, rail I of portion CIT, windings of relays AIR and BIR, rail Ia of the main control section, battery 8 in multiple with resistor 9, and rail Ia of section AIT, back to battery 1.

contact I6 of relay 2R, and the winding of relay Y ET to terminal N. The stick circuit for this relay is the same as the pickup circuit just traced eX- cept that it includes contact I1 of relay ET instead of contact I6 of relay 2R. Pickup and stick circuits are also closed for relay WT which are similar to the circuits just described for relay ET.

Relay XR is energized by a circuit passing from terminal B, through contacts 3R-2I, 2R23, and IP-24, and the Winding of relay XR to terminal N.

I shall assume that, with apparatus embodying my invention as shown in Fig. 1, an eastbound train enters preliminary section AIT, shunting battery I and completing a circuit for now energizing relays AIR and BIR by current of reverse polarity, this circuit passing from battery 8, through rail Ia of the main control section, windings of relays BIR and AIR, rail I of section portion C IT, jumper 5, rail I of section portion BIT, and through the Wheels and axles of the train, back to battery 8. The front contacts I4 and I5 of relay AIR therefore become open, whereas the front contacts 55 and BIR-3E of relay BIR become closed.

Although contact I4 of relay AIR is now open, relay IP remains energized by a second circuit, passing from terminal B, through contact 55 of relay BIR, and the winding of relay IP in multiple with resistor r, to terminal N.

Relay ET is now deenergized because contact I5 of relay AIR is opened.

With the back contact AIR-29 of relay AIR closed, and the front contact BIR-30 of relay BIR closed, a pickup circuit is completed for relay ITS, passing from terminal B, through contact 28 of relay WS, contacts AIR-29 and BIR-30, and the winding of relay ITS to terminal N. Relay ITS, upon becoming energized, completes its own stick` circuit which is the same as the pickup circuit just traced except that it includes contact 3| of relay ITS instead of contact BIR-3D.

Relay ITS, upon becoming energized, completes a pickup circuit for relay I-ZS, this circuit passing from terminal B, through contact 32 of relay ITS, front point of contact ZR-33, and the winding of relay I-ZS to terminal N.

When the train enters section portion BIT, battery 8, as well as battery I, will be shunted, so that relays AIR and BIR will both be deenergized, causing relay IP to also be deenergized. With relay BIR deenergized, the pickup circuit traced for relay ITS becomes opened at contact BIR-38, but relay ITS remains energized by its stick circuit previously described. With relay IP deenergized, the circuit traced for relay XR is opened at contact IP-24 so that relay XR is` deenergized, and starts the operation of bell G by closing its operating circuit passing from terminal B, through contact XR-35, and the mechanism of bell G to terminal N.

With relay IP deenergized and relay I-ZS energized, a pickup circuit is closed for energizing relay YS, this circuit passing from terminal B, through contact 35 of relay I-ZS, front point of contact ZR-3'I, contact IP-38, contact 39 of timeelement device 'IiRwinding of relay YS, and front pointofcon-tact ZR-III to terminal N. Relay YS, upon ybecoming energized, :completes its own stick circuit which is the `same as the pickup circuit just traced except that it includes contact 4) of relay YS instead of contact 39 of time element device TE.

Relay YS, upon becoming energized, completes a circuit for energizing time element device TE, this .circuit passing from terminal B, through contact 42 of 'relay YS, and the winding of time element device Tl? to terminal N.

I shall assume further that the :train proceeds at such speed that time element device TE does not close its contact 2,? tbefore the train enters section ZT, deenergizing relay ZR. With relay ZR .deenergizech the pickup circuit previously traced for .rel-ay I-ZS is opened Aat the front point of contact ZR-3S, but relay AI-ZS is of the slow releasing type so that its front contacts 34 and 36 remain closed until its stick circuit becomes closed, passing from terminal B, through contact 32 of relay ETS, Contact 3d of relay I-ZS, back point oi Contact ZR-S, and the winding of relay I-ZS to terminal N. The front contacts 34 and 3G of relay I-ZS are then retained closed by the stick circuit just traced for this relay.

When relay ZR becomes deenergized, the circuits previously described for relay YS are opened at the front points of contacts ZR-S'i and ZR-lil, and current oi reverse polarity is then supplied to the winding of relay YS through the back points of contacts ZR-S'I and ZR4I, causing the front contacts is and i2 of relay YS to be opened for a brief period oi' time. Time element device TE is of a type, which, upon becoming deenergized, returns quickly to its initial position, so that after contact 42 of relay YS again closes the energizing circuit for time element device TE, the timing period of device TE is started over. On account of section ZT being shorter than the distance between trucks of railway cars, relay ZR will be repeatedly deenergized and energized alternately while the train moves over section ZT, causing relay YS and, in turn, time element device TE, to be repeatedly deenergized.

As is well known, reversal of the polarity of the energizingY current for a neutral relay insures that the electromagnetic flux in the relay will pass through zero, and that therefore the relay armature will be released, whereas if energizing current of a given polarity only is merely interrupted for a brief period of time, the electromagnetic iiux in the relay may not go down all the Way to zero, and therefore the relay armature may not be released. It is for this reason that the circuits for relay YS are arranged so that the direction of flow of energizing current `through the winding of relay YS is reversed by relay ZR, instead of energizing current of a lgiven polarity through the winding of relay YS being merely interrupted, for a brief period of time. by relay ZR.

I shall also assume further that the train enters section 2T before time element device TE closes its contact 2'! after `the train has left section ZT. Contact 2Rf-23 is therefore now open in the circuit previously traced for relay XR, so that relay XR remains deenergized, and the operation of bell G is continued.

Relay 2R, upon becoming deenergized when the train enters section 2T, completes a pickup circuit for relay ES, this circuit passing from terminal B, through the back point of contact 43 of relay ET, contact 44 of relay 2R, front Vpoint of 75 contact `45 of relay'W'I, Vcontact WS-46, and the winding of relay ES to terminal N. Relay ES, upon .becoming energized, completes its own stick circuit, which is the same as the pickup circuit just traced except that it includes contact 4'I of relay ES instead of contact 45 of relay WT and contact WS-46.

When the train enters section 3T, relay 3R becomes deenergized, and, by opening its contact I8, in turn deenergizes relay WT. Relay WT, upon becoming deenergized, opens the pickup circuit previously traced for relay ES, but completes a second stick circuit for relay ES, passing from terminal B, through the back point of contact 45 of relay WT, contact 47 of relay ES, and the winding of relay ES to terminal N.

When the train leaves the main control section west of section 2T, relay AIR again becomes operated by its circuit previously traced, causing relay IP to again be energized by its circuit first traced. Relay AIR, upon opening its back contact AIR-29, deenergizes relay ITS, which, in turn, deenergizes relay I-ZS, and relay I-ZS in turn deenergizes relay YS. Time element device TE then becomes deenergized on account of relay YS being deenergized- When the train leaves section 2T, the stick circuit first traced for relay ES becomes opened at contact 44 of relay 2R, but relay ES then remains energized by its second stick circuit. Also, when the train leaves section 2T, relay ET becomes energized by its pickup and stick circuits previously traced. Relay 2R, upon becoming energized, completes a circuit for energizing relay YR, which is the same as the circuit rst traced for this relay except that it includes contact ES-ZZ instead of contact 3R-2 I. Relay YR, upon thus'becoming energized, opens the operating circuit for bell G at contact XR-35, thereby stopping operation of bell G.

When the train leaves section 3T, relay WT again becomes energized by its pickup and stick circuits previously described. Relay WT, Iupon becoming energizechopens the second stick circuit traced for relay ES, thereby deenergizing relay ES. With relay 3R again energized, the circuit rst traced for relay XR is again closed, so that although relay ES is now deenergized, relay XR remains energized, and therefore signal G remains inoperative.

I shall Ynext assume that, with al1 parts of the apparatus again in the normal condition, an eastbound train moves over section AIT and enters portion BIT of the main control section, causing operation of the bell to start, as previously described, and effecting energization of relay YS and time element device TE. I shall assume further, vthat the train stops on portion BIT, or that it moves so slowly that time element device TE closes its contact 21 before the train enters section ZT. Contact 21, upon becoming closed, completes a circuit for-energizing relay XR, this circuit passing from terminal B, through contacts 3R-2 I, 2R-23, YS-26, contact 2l of time element device TE, and winding-of relay XR to terminal N. Relay XR, upon thus becoming energized, interrupts the operation of bell G.

When the train resumes its movement toward the intersection of the railway track and highway H, and enters section ZT, relay YS becomes deenergized for a brief period of time because of the deenergization of relay ZR. Time element device TE is in turn deenergized for` a brief period of time and returned to its normal condition, so that its contact 27 opens `the `circuit g traced for relay XR, causing relay XR to be deenergized, which starts operation of bell G again. The operation of the apparatus as the train proceeds over the crossing will now be as previously described.

If, instead of stopping on section BIT before entering section ZT, the train stops with one pair of wheels on section ZT, causing relay ZR to remain deenergized, relay I-ZS will remain energized by its stick circuit previously traced. With relay ZR deenergized, relay YS will now be energized by a. pickup circuit passing from terminal B, through contact 36 of relay I-ZS, back point of contact ZR-QI, winding of relay YS, contact 39 of time element device TE, contact IP-38, and the back point of contact ZR-SI to terminal N. With relay YS energized, time element device TE will be energized by its circuit previously described. Upon the lapse of a measured period of time, device TE will close its contact 2l, thereby energizing relay XR and interrupting the operation of bell G, as previously described.

When the train again resumes its movement toward highway H, relay ZR will first become energized, thereby momentarily deenergizing relay YS, and then reversing the polarity of energization of relay YS, so that time element device ST will be returned to its normal condition as previously described, and will thereby deenergize relay XR and start the operation of bell G over again.

From the foregoing description of operation of the apparatus shown in the accompanying drawings, it follows that my invention provides means for insuring operation of a highway crossing signal in event of failure of portions of the control apparatus.

If, for example, a connection should become broken between the rails of section portion CIT and the windings of relays AIR and BIR, relay ITS would not become energized because Contact BIR-Sii in its pickup circuit would remain open. Relays I-ZS and YS, and time element device TE would therefore also remain deenergized. With both relays AIR and BiR deenergized, relay IP would be deenergized, and therefore relay XR would be deenergized because contact IP-24 would be open. Operation of bell G would therefore be initiated, and would not be interrupted by time element device TE, so it would be continuous. That would indicate something was wrong, and so a signal maintainer would take the necessary action for correcting the condition.

It follows that the purpose of the arrangement embodying polarity responsive means, such for example as two biased neutral track relays AIR and B IR for the approach control stretch west of section 2T is to prevent energization of time element device TE in the event of a broken track circuit connection for this approach control stretch. If only one ordinary neutral track relay were used for starting the operation of time element device TE, deenergization of the one track relay because of a broken connection would effect operation of the time element device TE, and when an eastbound train subsequently arrived on this approach control stretch, the highway crossing signal would therefore not be operated.

The purpose of relay ITS is to check the correct operation of relays AIR and BIR. In order for relay ITS to become energized by its pickup circuit, relay AIR must become deenergized and relay BIR must become energized. If both relays AIR and BIR should become deenergized at the same time, due to a broken track circuit connec- 10 tion, relay ITS would not become energized, and therefore the time element device TE would not become energized.

The purpose of the directional relays ET, WT, ES and WS is to stop the operation of the highway crossing signal G as soon as a train has moved off of the crossing section 2T, and while it is moving away from the intersection over the approach control section 3T east of section 2T or over the approach control stretch west of section 2T.

If relay ZR would be falsely deenergized, its contact ZR-BS would be open in the pickup circuit for relay I-ZS. Relay YS and time element device TE would therefore remain deenergized. Relay XR would therefore also remain deenergized and cause bell G to be operated continuously, and not be interrupted while a train stands on the main control section, until the condition is corrected by a signal maintainer.

I shall now assume that all parts of the apparatus are again in the normal condition, and that a westbound train enters section 3T, deenergizing relay 3R, and thereby in turn deenergizing relay WT. With relay 3R deenergized, the circuit rst traced for relay XR will be opened at contact 3R-2 I, causing relay XR to become deenergized, which, in turn causes bell G to be operated.

When the train enters section 2T, relay WS becomes energized by its pickup circuit passing from terminal B, through the back point of contact 45 of relay WT, contact 44 of relay 2R, front point of contact II3 of relay ET, contact ES-46, and the winding of relay WS to terminal N. Relay WS, upon becoming energized, completes its own stick circuit which is the same as the pickup circuit just traced except that it includes Contact 51 of relay WS instead of the front point of contact 43 of relay ET and contact ES-IIB.

When the train enters portion C IT 0f the main control section, relay AlR becomes deenergized, and in turn deenergizes relay ET. Relay ET, upon becoming deenergized, opens the pickup circuit traced for relay WS, and completes a second stick circuit for this relay, passing from terminal B, through the back point of contact i3 of relay ET, contact 51 of relay WS, and the winding of relay WS to terminal N. Since relay WS is energized, its back contact 28 is open in the circuits previously traced for relay ITS. With relay ITS deenergized, relay I-ZS and, inA turn, relay YS will remain deenergized. With relay YS deenergized, time element device TE remains deenergized. It follows that time element device TE does not become energized for westbound trac movements.

When the train leaves section 3T, relay 3R becomes energized and, when the train leaves section 2T, relay 2R becomes energized, thereby completing the pickup circuit previously traced for relay WT. With relay 2R energized, relay XR is now energized by a circuit passing from terminal B, through contacts SR-ZI, 2R23, and WS-25, and the winding of relay XR to terminal Relay XR, upon thus becoming energized, opens the operating circuit for bell G, thereby stopping the operation of the bell.

I have described the operation of the apparatus for a few typical traic movements. It is believed that, in view of the foregoing description, the operation of the apparatus as shown in Fig. l, or as modified as shown in Fig. 2 or Fig. 3, can be readily followed for any other possible tramo movements by referring to the drawings.

Although I have herein shown and described 1l only a few forms of apparatus embodying my invention, it is understood that various changes and modications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, including a given control section of said railway track divided into a main portion and an intermediate portion, and including means controlled by a train approaching said intersection for starting operation of said highway crossing signal while said train occupies said given control section, the combination comprising, time element means energized for interrupting operation of said highway crossing signal if said train occupies said given control section longer than a given measured period of time, means responsive to said train upon moving over said intermediate portion of said given control section for then deenergizing said time element means and thereby rendering said time element means ineiective to interrupt further the operation of said highway crossing signal, and direction control means controlled by a train moving in the opposite direction over said given control section to prevent energization f said time element means.

2. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, including means controlled by a train approaching said intersection in a given direction for starting operation of said highway crossing signal, the combination comprising, time element means controlled by said train for repeatedly interrupting operation of said highway crossing signal if said train repeatedly stops approaching said intersection after starting loperation of said highway crossing signal, means responsive to said train each time it resumes movement toward said intersection for deenergizing said time element means and thereby rendering said time element means inelTective to interrupt the operation of said highway crossing signal, and direction controly means controlled by a train moving in the opposite direction to prevent operation of said time element means while said train moving in the opposite direction is receding from said intersection.

3. In a control system for a highway crossing signal adjacent the intersectionof a railway track with a highway, the combination comprising, a control stretch of said railwayv track divided by an insulated joint in one rail of said stretch into a preliminary section and a main section between said preliminary section and said intersection, an intermediate portion of said main section divided into an intermediate section which is shorter than the distance between trucks of a railway car, a track circuit for said stretch including said preliminary section and the rails of said main section connected around said intermediate section and including al main source of current of a given potential connected across the rails of said preliminary section with an auxiliary source of current of opposite and lowei` potential connected around said insulated joint and also including two biased neutral relays connected in series opposition across the opposite end of said main section so that the front contacts of one of said relays are normally closed in response to current from said main source and the front contacts of the other of said relays become closed in response to current from said auxiliary source when a train enters said preliminary section, a checking stick relay controlled to become energized if said one relay is deenergized and said other relay is energized in response to a train approaching said intersection in a given direction only and said checking stick relay then controlled to remain energized after said other relay becomes deenergized, a repeater relay controlled by a front contact of each of said biased neutral relays connected in multiple with each other, a timing stick relay controlled by a front contact of said checking stick relay and by a back contact of said repeater relay and momentarily deenergized when said intermediate section becomes occupied, time element means controlled by said timing stick relay, means controlled by a train upon entering said main section for starting operation of said highway crossing signal, and means controlled by said timing stick relay and by said time element device for interrupting operation of said highway crossing signal if a train approaching said intersection in a given direction only stops on said main section and for again starting operation of said highway crossing signal when the train resumes movement toward said intersection.

4. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising,v a control stretch of said railway track divided into a crossing section at said intersection and an approach control stretch comprising a preliminary section and a main section between said preliminary sectionV and said crossing section, polarity responsive means connected across the rails of said main section, means for normally supplying current of a given polarity to the rails of said main section but for supplying current of the opposite polarity to the rails of said main section when a train enters said preliminary section, means controlled by said polarity responsive means when a train enterssaid main section for starting operation of said highway crossing signal, time element means controlled by said polarity responsive means for interrupting operation of said signal upon the lapse of a measured period of time after a train approaching said intersection in a given direction only enters said main section, traffic responsive means operable in response to said train moving over an intermediate portion of said main section, means controlled by said traic responsive means upon becoming operated in response to said train moving over the intermediate portion of said main section for eiTecting deenergization of said time element means, operation of said highway crossing signal being then again started by said means controlled by said polarity responsive means while said train proceeds further on said main section, and means controlled by said train on said crossing section for then continuing the operation of said signal while said train is passing over said intersection.

5. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising, a control stretch of said railway track divided into a crossing section at said intersection and an approach control stretch comprising a preliminary section and a main section between said preliminary section and said crossing section, polarity responsive means connected across the rails of said main section, means for nor- `accesos mally supplying current of a given polarity to the rails of said main section but for supplying current of the opposite polarity to the railsrof said main section when a train enters said preliminary section, means controlled by said polarity responsive means when a train enters said main section for starting operation of said highway crossing signal, means controlled by said polarity responsive means for interrupting operation of said signal if said train stops on said main section while approaching said intersection in a given direction only, means controlled by said train for again starting operation of said signal when said train resumes its movement toward said intersection, and means controlled by said train on said crossing section for then continuing the operation of said signal while said train is passing over said intersection.

6. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising, a control stretch of said railway track divided into a preliminary section and a main section between said preliminary section and said intersection, polarity responsive means connected across the rails of said main section, means for normally supplying current of a given polarity to the rails of said main section but for supplying current of the opposite polarity to the rails of said main section when a train enters said preliminary section, means controlled by said polarity responsive means when a train enters said main section for starting operation of said highway crossing signal, time element means controlled by said polarity responsive means for interrupting operation of said signal upon the lapse of a measured period of time after a train approaching said intersection in a given direction only enters said main section, and means controlled by said train upon moving over a given portion of said main section for deenergizing said time element means for again starting operation of said signal.

7. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising, a control stretch of said railway track divided into a preliminary section and a main section between said preliminary section and said intersection, polarity responsive means connected across the rails or said main section, means for normally supplying current of a given polarity to the rails of said main section but for supplying current or the opposite polarity to the rails of said main section when a train enters said preliminary section, means controlled by said polarity responsive means upon becoming deenergized when a train enters said main section for starting operation of said highway crossing signal, time element means controlled by said polarity responsive means for interrupting operation of said signal upon the lapse of a measured period of time after a train approaching said intersection in a given direction only enters said main section, and traflic responsive means operated in response to said train moving over an intermediate portion of said main section for deenergizing said time element means for again starting operation of said signal.

8. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising, a control stretch of said railway track divided into a preliminary section and a main section between said preliminary section and said intersection, two biased neutral relays connected in series opposition across the rails of said'main section so that one of said relays closes its front contacts in response to current of a given polarity only and the other of said relays closes its front contacts in response to current of the opposite polarity only, means for normally supplying current of said given polarity to the rails of said main section but supplying current of the opposite polarity to the rails of said main section when a train enters said preliminary section, a checking stick relay, a pickup and a stick circuit for said checking stick relay each controlled by a back contact of said one relay and said pickup circuit also controlled by a front contact of said other relay, means controlled by said biased neutral relays when a train enters said main section for starting operation of said highway crossing signal, time element means controlled by means including a front contact of said checking stick relay for interrupting operation of said signal upon the lapse of a measured period of time after a train approaching said intersection in a given direction only enters said main section, and means controlled by said train upon moving over a given portion of said main section for again deenergizing said time element means for again starting operation of said signal.

9. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising, a control stretch of said railway track divided into a preliminary section and a main section between said preliminary section and said intersection, two biased neutral relays connected in series opposition across the rails of said main section so that one of said relays closes its front contacts in response to current of a given polarity only and the other of said relays closes its front contacts in response to current of the opposite polarity only, means for normally supplying current of said given polarity to the rails of said main section but supplying current ofthe opposite polarity to the rails of said main section when' a train enters said preliminary section, means controlled by said relays when a train enters said main section for starting operation of said highway crossing signal, an intermediate portion of said main section divided to form an intermediate section which is shorter than the distance between the trucks of a railway car, a track circuit for said intermediate section including a track relay, a checking stick relay, a pickup and a stick circuit for said checking stick relay each controlled by a contact which is controlled by said biased neutral relays to become closed when a train enters said preliminary section and to remain closed while the train occupies said main section and the pickup circuit also controlled by a front contact of said track relay for said intermediate section, time element means controlled by means including a front contact of said checking stick relay for interrupting operation of said signal upon the lapse of a measured period of time after a train approaching said intersection in a given direction only enters said main section, and said time element means also controlled by said track relay for said intermediate section for again starting operation of said signal when said train moves over said intermediate section.

10. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, the combination comprising, a control stretch of said railway track divided into a preliminary section and a main secv15 tion between said preliminary section and said intersection, two biased neutral relays connected in series opposition across the rails of said main section so that one of said relays closes its front contacts in response to current of a given polarity only and the other of said relays closes its front contacts in response to current of the opposite polarity only, means for normally supplying current of said given polarity to the rails of said main section but for supplying current of the opposite polarity to the rails of said main section when a train `enters said preliminary section, means controlled by said relays when a train enters said main section for starting operation of said highway crossing signal, a checking relay, means controlled by said biased neutral relays for energizing said checking relay only if said other relay is energized while said one relay is deenergized and for then retaining said checking relay energized While said one relay is deenergized, time element means, means controlled by a front contact of said checking relay and by said other relay upon becoming deenergized when a train approaching said intersection in a given 1'6 direction only enters vsaid main section for energizing said time element means, means controlled by said time lelement means for interrupting operation of said signal upon the lapse of a measured period of time after said train enters said main section, and means controlled by said train .upon moving over a given portion of said main section for deenergizing said time element means to again start operation of said signal.

JAMES E. MCMAHON, JR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,933,690 Young Nov. 7,r 1933 1,937,773 Mishelevich Dec. 5, 1933 2,021,654 Kemmerer et al. Nov. 19, 1935 2,346,518 Tizzard Apr. l1, 1944 2,379,209 Allen June 26, 1945 2,452,868 Quinlan Nov. 2, 1948 

